•Single-phase Ni2Si was prepared by temperature programmed pyrolysis method.•Catalytic activity of Ni2Si depends on pyrolysis temperature, flow, and Si/Ni ratio.•Selectivity to ST is ca. 90% in hydrogenation of PA on the single-phase Ni2Si.•Alkali treatment improves significantly the catalytic activity of Ni2Si.

A single-phase Ni2Si nanoparticle catalyst was prepared successfully by using temperature programmed pyrolysis method with polydimethylsilane-Ni(acac)2 as precursor and was characterized by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron emission microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The pyrolysis temperature for generating pure Ni2Si in H2/Ar mixture is significantly lower than that for treatment in Ar. Ni2Si nanoparticles would be reduced to Ni nanoparticles by H2 with increasing pyrolysis temperature (>600 °C). The catalytic hydrogenation of phenylacetylene on Ni2Si nanoparticles was investigated at 1.0 MPa hydrogen and 80 °C. The catalysts show suitable conversion of phenylacetylene and notable selectivity to styrene with 90%. In addition, catalytic performance on Ni2Si prominently improves after removing the SiO2 layer around Ni2Si nanoparticles by alkali treatment.